Microstructure–properties relationship in ceramic–elastomer composites with 3D connectivity of phases

The ceramic–elastomer composites with 3D phase connectivity were tested under compressive loads. Such composites exhibit high initial strength and stiffness with the ability to sustain large deformations. Samples of the composites were made of porous SiO₂ ceramic matrix infiltrated by polyurethane elastomer. The ceramic matrix preforms used differed in the porosity and three different composite microstructures have been obtained. Selected parameters of microstructure composites were evaluated using image analysis. The compressive strength and capacity for energy absorption are characterized under various strain rates (0.001–235 s⁻¹). It was found that stress–strain characteristic depends on the strain rate and the specific interface area (Sv). Pore size and the specific interface area have a strong effect on the compressive strength of composites and these parameters can be used for tailoring their mechanical properties. The acoustic emission was applied to identify stages in the process of microstructure damage during compression. The interpretation of damage stages was proposed, which also explains the character of the stress–strain curves.